During the refueling of vehicles, in particular aircraft, especially military aircraft, large amounts of fuel must be transferred in a very short period of time from a hydrant system or a tank truck into the tank to be filled on a vehicle or aircraft. Problematic during refueling are the last twenty to thirty meters, which are to be overcome from the refueling truck or the hydrant system to the tank to be filled.
To overcome this problem, it is known to use hoses, which have couplings at their ends, so that the refueling operation can occur directly after the connection to the fill opening of the respective tank. Hoses having a steel or Perlon insert are used, which as a rule have nominal widths of 21/2 to a maximum of 3". However, handling of these hoses becomes more difficult and complicated with increasing nominal widths and longer hoses. With lengths of over 20 m., one is therefore forced to utilize hoses with smaller diameters, since these would otherwise hardly be manageable due to their heavy weight, because the hoses must be pulled or carried. A transport of the hoses from ony hydrant connection to the next one is as a rule hardly possible in the unrolled state, because the hoses must then be pulled over the ground, which, however, does not only require a high amount of force, but also significantly reduces the lifetime of the hoses because of the high friction with the ground.
It the hoses are stored in refueling shafts, they are exposed to additional wear, because they must be pulled over the edge of the shaft when they are being pulled out. Aside from these mechanical damages, the hoses also are exposed to a relatively great alteration process, so that these for safety reasons alone must be replaced periodically after a certain duration of use.
A further, by all means significant disadvantage in the use of hoses is that their use for defueling is very limited and that they can only be used in expensive special designs. Moreover, the hoses can be emptied only through complicated lifting. In particular, it has proven to be disadvantageous to connect the hoses to the aircraft refueling coupling due to the difficulty of handling a heavy weight and the tension of the hoses and, on the other hand, to expose the refueling coupling to a high moment through the hoses, which can result in damage.
Furthermore, pressure reliefs in hoses can be realized only with great difficulty. However, pressure reliefs are needed, since the high expansion coefficient of aircraft fuel causes a large volume increase due to the thermal effect. The thus caused pressure increase stretches the hoses, so that they can no longer be bent. Whereas dropping temperatures create an under pressure in the hoses, so that they can collapse and their reinforcements can break.
Furthermore hydrant vehicles with refueling armatures are known, which can be connected through hoses both to the hydrant and also the refueling coupling of the aircraft. The disadvantage of this hydrant vehicle consists in it, on the one hand, needing the hoses with the aforementioned disadvantages and, on the other hand, needing a separate energy source for winding up the hoses and to also increase the pressure in hose lines having a small cross section.
The above-disclosed disadvantages in using hoses for refueling show that, aside from the difficulties in handling and from the high wear which is to be expected, the refueling duration can hardly be further increased by the increase of the nominal widths of the hose, if one considers the disadvantage in the handling created by the increase of the nominal widths. Hoses represent, because of these susceptibilities and their sensitivity of heat, a high safety risk, in particular during use near running turbines and motors, as this is the case during the quick refueling of fighter aircraft. The described disadvantages require at the same time an intensive servicing and testing operation, which must occur prior to and after each refueling operation.
Therefore, the basic purpose of the invention is to provide a refueling system of the above-mentioned type, in which hoses are not needed and thus the handling difficulties caused by their use, greater wear and safety risks because of heat sensitivity do not exist, and which can be manufactured less expensively and has a greater durability without intensive servicing and testing operations. It furthermore has a high degree of flexibility in certain refueling areas, in particular in aircraft refueling, and its handling during refueling in the highest areas, for example during an under-wing refueling of certain aircraft types, is possible with less use of energy.
The advantages achieved with the invention consist substantially in hoses not being needed, since they, as is known, are difficult to handle and because of their heat sensitivity represent a high safety risk, in particular during their use near running turbines and motors, as this is the case during the quick refueling of fighter aircraft. The inventive refueling system can be manufactured inexpensively and has, because of less wear, a longer durability than the usual refueling systems which operate with hoses. Also, the servicing and testing operations of the inventive refueling system are much shorter than in the known systems. Due to the fact, that the inventive refueling system is equipped with a refueling tip and swivel joints, it has a high flexibility in particular at connecting heights of approximately 2.2 m. Through the initial tension of concussion springs of a concussion-spring unit, the refueling tip of the refueling system is balanced such that it always assumes the maximum deflection. Handling during refueling in the highest area, that is at approximately a 4.7 m. height, is possible with little use of energy, because only the weight of the uppermost tip of a combination consisting of three joints must be held and moved. Due to the fact that each horizontal and vertical movement of a refueling coupling can be converted into a rotary movement, it is assured that practically no forces or loads are transmitted onto the coupling on the aircraft. The inventive refueling system equipped with the refueling tip can be used universally for refueling heights of approximately 0.8 m (tank truck) and up to a height of 4.7 m., namely also for under-wing refueling, and is thus well suited for aircraft such as the DC 10, B747 and A300.